Tonk is close. You don't actually need the Palace built per se, but you do have to have your "Expansion" research finished. This reasearch lets you ship goods to (and pillage from ) far off islands. The "Expansion" research allows you to build the Palace as well which is used to build new colonies but the Palace does not have to be built to be able to send your trade ships afar.
) far off islands. The "Expansion" research allows you to build the Palace as well which is used to build new colonies but the Palace does not have to be built to be able to send your trade ships afar.
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